Either draw the minion with marker or take a print out of the preferred size. You can also make two or three by reducing the size. Then place the paper under the shirt, the outline will show through, first draw the entire outline.
Let it dry, remove the paper and place a plastic sheet or foil to prevent the paint from getting on to the other side, spread the navy, white and silver with brush, your last touch will be the eyes and the thread lines od the jean dress. Let one color dry before you the other.